The present invention is related to herbicidal agents and to plant growth regulators containing as active ingredient the complex of a benzene sulphonyl urea derivative of the general formula (II) ##STR3## and of .beta.-cyclodextrin of the formula (I) ##STR4## as well as the use of these compositions in plant protection and a process for the preparation of the active ingredient complexes.
Related to 1 mole of the benzene sulphonyl urea derivative of the general formula (II) at least 2 moles of cyclodextrine are needed in order that the whole amount of the sulphonyl urea forms a cyclodextrine inclusion complex. Accordingly the new complex of the invention is an inclusion complex of 1 mole sulphonyl urea derivative of the general formula (II) with 2 or more cyclodextrine molecules.
In the general formula (II)
X stands for halogen or --COOR-- wherein R stands for an aliphatic group; PA1 Y and Z independently of each other stand for hydrogen, C.sub.1-4 alkyl or C.sub.1-4 alkoxy and PA1 A represents a --CH.sub.2 -- group or nitrogen atom. PA1 R preferably stands for alkyl, alkenyl or alkinyl having up to 4 carbon atoms particularly methyl, ethyl or propyl. As halogen chlorine is preferred. Y and Z preferably stand for methyl or methoxy.
In U.S. Pat. Nos. 4,169,719 and 4,127,405 benzene sulphonyl urea derivatives of the general formula (II) were described as active ingredients of selective herbicidal agents--wherein X, Y, Z and A are as given above--. Due to the high efficiency they are suitable for application in small amounts related to 1 ha and their use is also favourable from the point of view of toxicity. Both their acute and chronic toxical dosage are extremely high [J. Agric. Food Chem. 29, 416 (1981)]. In certain cases when using higher dosages it was observed that the decomposition of the active ingredients is very slow and so in case of sensitive plant cultures the persistance of the active ingredients should be taken into account [Byeung Hoa Kang: Verhalten and Verbleib Sowie Ursachen fur die selektive Wirkung von Chlorsulfuron in Kulturpflanzen and Unkrautern, Inst. fur Phytomedizin der Univ. Hohenheim DBR, September 1983].